All practice questions

4736 questions

Question 2601Question →

A 68-year-old woman presents to the clinic with a 4-month history of progressive fatigue and a "pins and needles" sensation in her feet. Her past medical history is significant for type 2 diabetes mellitus, for which she has been taking metformin for 8 years. Physical examination reveals a smooth, glossy red tongue and decreased vibratory sensation in the bilateral lower extremities. The Romberg test is positive.

Laboratory studies show:
TestResultReference Range
Hemoglobin10.4 g/dL12.0-15.5 g/dL
Mean corpuscular volume112 fL80-100 fL
Serum vitamin B12245 pg/mL200-900 pg/mL
Serum folate14 ng/mL> 4 ng/mL

Which of the following is the most appropriate next step in laboratory evaluation?

Show answer & explanation

Answer: Measurement of serum methylmalonic acid

Answer

Measurement of serum methylmalonic acid
The correct answer is measurement of serum methylmalonic acid. This patient has classic symptoms of vitamin B12 deficiency, including macrocytic anemia, glossitis, and subacute combined degeneration (neuropathy and a positive Romberg test). Long-term metformin use is a well-known risk factor for B12 malabsorption. Her serum B12 level is borderline (between 200 and 300 pg/mL). In cases where clinical suspicion is high but the serum level is equivocal, assessing a functional marker of B12 is required. Vitamin B12 is an essential cofactor for the conversion of methylmalonyl-CoA to succinyl-CoA. Therefore, in true tissue-level B12 deficiency, serum methylmalonic acid (MMA) accumulates and is elevated. This test will definitively establish the diagnosis.

Step-by-Step Solution

1
Analyze the patient's clinical presentation.
Symptoms of macrocytic anemia, glossitis, and peripheral sensory neuropathy point strongly toward vitamin B12 deficiency, with chronic metformin use acting as a major risk factor.
To establish a pre-test probability before interpreting laboratory results.
2
Interpret the initial laboratory findings.
The patient has macrocytic anemia with a borderline serum vitamin B12 level (200-300 pg/mL) and a normal folate level.
A borderline B12 level does not definitively rule in or rule out a clinical deficiency.
3
Determine the appropriate diagnostic test to confirm tissue-level deficiency.
Order a serum methylmalonic acid (MMA) level, which will be elevated in true B12 deficiency.
MMA is a precursor that requires B12 as a cofactor for metabolism; its accumulation confirms functional deficiency at the cellular level.

Key Concept

In patients with high clinical suspicion for vitamin B12 deficiency but borderline initial serum B12 levels (200-300 pg/mL), measurement of serum methylmalonic acid (MMA) is the most appropriate next step to confirm the diagnosis.
Question 2602Question →

A 24-year-old previously healthy woman presents to the emergency department with a 2-hour history of severe, sudden-onset, right-sided pelvic pain. She reports that her last menstrual period was 6 weeks ago and she noticed light vaginal spotting this morning. Vital signs show a blood pressure of 88/54 mmHg, a heart rate of 122/min, and a respiratory rate of 22/min. Abdominal examination demonstrates right lower quadrant tenderness with voluntary guarding and rebound tenderness. Arrange the following differential diagnoses in order from the highest pre-test probability (most likely and most urgent) to the lowest pre-test probability based on this patient's clinical presentation.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order from most to least likely is: Ruptured ectopic pregnancy, Ruptured hemorrhagic ovarian cyst, Ovarian torsion, and Acute appendicitis.
Based on the clinical presentation, the most urgent and likely diagnosis is a ruptured ectopic pregnancy due to the classic triad of delayed menses, vaginal bleeding, and acute pelvic pain, combined with hemorrhagic shock. A ruptured hemorrhagic ovarian cyst is next as it can also cause hemoperitoneum and shock, but the missed menses makes ectopic more probable. Ovarian torsion causes sudden pain but lacks significant blood loss to cause shock. Acute appendicitis is the least likely as its pain is typically gradual in onset and it does not explain the gynecologic symptoms or the severe early shock.

Step-by-Step Solution

1
Analyze the primary symptoms and vital signs.
The patient has acute, severe right-sided pelvic pain, a 6-week missed period, vaginal spotting, and signs of hypovolemic shock (hypotension and tachycardia).
Identifying the classic triad of ectopic pregnancy (amenorrhea, vaginal bleeding, abdominal pain) combined with hemodynamic instability is crucial for prioritization.
2
Identify the most acutely life-threatening and highly probable condition.
Ruptured ectopic pregnancy perfectly matches the triad of symptoms and the presence of shock, placing it first.
Immediate surgical intervention or resuscitation is required; failure to prioritize this leads to mortality.
3
Evaluate the remaining options for their ability to cause shock and acute pain.
A ruptured hemorrhagic ovarian cyst can cause similar acute pain and hemoperitoneum (shock), but lacks the strong association with amenorrhea, placing it second.
Both conditions cause intra-abdominal bleeding, but the missed period makes ectopic pregnancy the primary suspect.
4
Differentiate the final two conditions based on presentation severity.
Ovarian torsion causes sudden pain but rarely shock. Acute appendicitis typically has a gradual onset and does not cause vaginal spotting or early shock.
Torsion is an acute ischemic event (more sudden than appendicitis), placing it third, while appendicitis is placed last due to incompatible symptom progression.

Key Concept

In a female of reproductive age presenting with a missed period, vaginal spotting, sudden-onset abdominal pain, and hypovolemic shock, ruptured ectopic pregnancy is the primary and most urgent differential diagnosis until proven otherwise.
Question 2603Question →

A 3232-year-old woman is brought to the emergency department by emergency medical services after being stung by a bee. She has a history of severe bee sting allergy. On arrival, her blood pressure is 80/5080/50 mm Hg, heart rate is 125125/min, and respiratory rate is 2828/min. She has diffuse urticaria, facial swelling, and prominent expiratory wheezing. Arrange the following pharmacologic interventions in the correct prioritized sequence of administration for the acute management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Intramuscular epinephrine, 2) Intravenous crystalloid fluid bolus, 3) Intravenous methylprednisolone and diphenhydramine.
In a patient presenting with anaphylactic shock (characterized by hypotension, bronchospasm, and mucocutaneous signs after an allergen exposure), the absolute first step is the administration of intramuscular epinephrine. Epinephrine's alpha-1 agonism increases systemic vascular resistance, while its beta-2 agonism causes bronchodilation and decreases mast cell degranulation. If hypotension persists, the next step is rapid volume expansion with intravenous crystalloid fluids to counteract the massive fluid shift caused by increased vascular permeability. Only after the patient's airway and hemodynamics are stabilized with epinephrine and fluids should adjunctive medications, such as intravenous corticosteroids (e.g., methylprednisolone) and antihistamines (e.g., diphenhydramine), be administered. These adjuncts help relieve cutaneous symptoms and may reduce the risk of a biphasic anaphylactic reaction, but they have no immediate life-saving role.

Step-by-Step Solution

1
Administer intramuscular epinephrine.
Reversal of upper airway edema, bronchoconstriction, and severe hypotension.
Alpha-1 and beta-2 agonist properties of epinephrine make it the only first-line medication proven to prevent mortality in anaphylaxis.
2
Administer an intravenous crystalloid fluid bolus.
Expansion of intravascular volume and improvement in blood pressure.
Anaphylactic shock often involves massive extravasation of intravascular fluid; aggressive volume resuscitation is needed if hypotension persists despite epinephrine.
3
Administer adjunctive intravenous corticosteroids and antihistamines.
Relief of urticaria and mitigation of delayed allergic responses.
These medications have a delayed onset of action and do not save lives in acute anaphylaxis; they must be given only after the airway and hemodynamics are secured.

Key Concept

In the management of anaphylactic shock, intramuscular epinephrine is the absolute first priority, followed by fluid resuscitation for persistent hypotension, and finally adjunctive medications like antihistamines and corticosteroids.
Question 2604Question →

A 4242-year-old woman is brought to the emergency department by her husband due to a 22-day history of progressive confusion and generalized weakness. She reports having a mild upper respiratory illness one week ago. Her temperature is 38.2∘C38.2^\circ\text{C} (100.8∘F100.8^\circ\text{F}), blood pressure is 130/80 mmHg130/80\text{ mmHg}, and pulse is 102/min102/\text{min}. Physical examination reveals scleral icterus and scattered petechiae on her bilateral lower extremities. Neurological examination shows intermittent disorientation to time and place, but no focal motor or sensory deficits. Laboratory studies show:

* Hemoglobin: 7.8 g/dL7.8\text{ g/dL}
* Platelets: 18,000/mm318,000/\text{mm}^3
* Leukocytes: 8,400/mm38,400/\text{mm}^3
* Creatinine: 1.1 mg/dL1.1\text{ mg/dL}
* Total bilirubin: 3.8 mg/dL3.8\text{ mg/dL} (Indirect: 3.1 mg/dL3.1\text{ mg/dL})
* Prothrombin time: 12 seconds12\text{ seconds} (Normal: 1111-14 seconds14\text{ seconds})
* Partial thromboplastin time: 28 seconds28\text{ seconds} (Normal: 2525-35 seconds35\text{ seconds})

Peripheral blood smear reveals numerous schistocytes.

Which of the following is the most likely diagnosis?

Show answer & explanation

Answer: Thrombotic thrombocytopenic purpura

Answer

Thrombotic thrombocytopenic purpura
The correct answer is Thrombotic thrombocytopenic purpura (TTP). This patient presents with four of the classic five features of the TTP pentad: microangiopathic hemolytic anemia (MAHA) evidenced by anemia, indirect hyperbilirubinemia, and schistocytes; severe thrombocytopenia (petechiae, low platelet count); neurologic manifestations (confusion, disorientation); and fever. The normal prothrombin time (PT) and partial thromboplastin time (aPTT) definitively distinguish this primary platelet microthrombi disorder from consumptive coagulopathies.

Step-by-Step Solution

1
Analyze the patient's presenting clinical signs and symptoms.
The patient has fever, neurologic abnormalities (confusion), and clinical evidence of thrombocytopenia (petechiae) and hemolysis (scleral icterus).
Identifying the systemic symptom clusters narrows the differential diagnosis for acute hematologic emergencies.
2
Evaluate the laboratory data and peripheral smear.
Labs confirm severe thrombocytopenia (18,000/mm318,000/\text{mm}^3) and microangiopathic hemolytic anemia (MAHA) indicated by anemia, elevated indirect bilirubin, and schistocytes.
Confirming MAHA distinguishes this process from immune-mediated extravascular hemolysis or isolated platelet destruction.
3
Assess organ function and coagulation profile to differentiate among MAHA causes.
Creatinine is normal (1.1 mg/dL1.1\text{ mg/dL}), making Hemolytic uremic syndrome (HUS) less likely. PT and aPTT are normal, ruling out Disseminated intravascular coagulation (DIC).
Normal renal function with dominant neurologic symptoms and normal coagulation times definitively points to Thrombotic thrombocytopenic purpura (TTP).

Key Concept

Formulating a differential diagnosis for microangiopathic hemolytic anemia by analyzing coagulation profiles and specific organ involvement.
Question 2605Question →

Match the following detailed radiological descriptions of imaging findings to their most likely underlying clinical condition.

Click a left item, then click its matching right item

Items

Macronodule surrounded by a perimeter of ground-glass opacity on high-resolution chest CT
Simultaneous dilation of the common bile duct and the main pancreatic duct on magnetic resonance cholangiopancreatography
Triangular area of contrast enhancement surrounding a central non-enhancing region in the superior sagittal sinus on brain CT venography
Alternating segments of focal luminal stenosis and aneurysmal dilation in the mid-to-distal renal artery on magnetic resonance angiography
Smooth, symmetric tapering of the distal esophagus with significant proximal dilation on barium esophagram

Matches

Show answer & explanation

Answer

The descriptions correspond to pathognomonic signs for Invasive pulmonary aspergillosis, Pancreatic head adenocarcinoma, Cerebral venous sinus thrombosis, Fibromuscular dysplasia, and Achalasia, respectively.
Each specific radiological description translates to a well-known pathognomonic 'sign' that correlates directly with a single specific underlying pathophysiology. The 'halo sign' points to invasive pulmonary aspergillosis; the 'double duct sign' to pancreatic head adenocarcinoma; the 'empty delta sign' to cerebral venous sinus thrombosis; the 'string of beads' to fibromuscular dysplasia; and the 'bird's beak' to achalasia.

Step-by-Step Solution

1
Analyze the chest CT finding of a macronodule with ground-glass opacity.
Identify the pattern as the 'halo sign'.
The ground-glass halo represents alveolar hemorrhage surrounding an invasive fungal infection, which is the pathognomonic finding of invasive pulmonary aspergillosis.
2
Evaluate the MRCP finding of dual ductal dilation.
Identify the pattern as the 'double duct sign'.
An obstructing mass at the pancreatic head causes upstream back-pressure, leading to simultaneous dilation of both the common bile duct and the main pancreatic duct, classically seen in pancreatic head adenocarcinoma.
3
Assess the CT venography finding of a non-enhancing center within a triangular enhancing region in the superior sagittal sinus.
Identify the pattern as the 'empty delta sign'.
The non-enhancing center is the occlusive thrombus, while the enhancing triangle is the collateral dural venous flow, confirming cerebral venous sinus thrombosis.
4
Examine the MR angiography finding of alternating stenosis and dilation in the renal artery.
Identify the pattern as the 'string of beads' sign.
This morphological change represents medial fibroplasia, the most common pathological variant of fibromuscular dysplasia.
5
Interpret the barium esophagram showing distal tapering and proximal dilation.
Identify the pattern as the 'bird's beak' sign.
This structural change results from incomplete lower esophageal sphincter relaxation and absent peristalsis, the hallmarks of achalasia.

Key Concept

Identifying classic pathognomonic imaging signs from their radiological descriptions and correlating them with their underlying clinical diagnoses.
Estimated Time:2m 0s
Question 2606Question →

A 45-year-old woman is evaluated in the emergency department for severe, progressive abdominal distension and right upper quadrant pain that began 4 days ago. She also reports intense, generalized itching that typically occurs after taking warm showers. Her past medical history is significant for peptic ulcer disease. She takes no medications. Her temperature is 37.2∘C37.2^\circ C (99.0∘F99.0^\circ F), blood pressure is 145/88145/88 mmHg, heart rate is 98/min, and respiratory rate is 18/min. Physical examination reveals a ruddy facial complexion. The jugular venous pressure is 66 cm H2OH_2O. Abdominal examination shows marked distension, shifting dullness, and a palpable, tender liver edge 55 cm below the right costal margin. There is no lower extremity edema.

Laboratory studies show:
Hemoglobin: 18.818.8 g/dL
Hematocrit: 56%
Leukocytes: 12,500/μL12,500 / \mu L
Platelets: 620,000/μL620,000 / \mu L
Serum total protein: 6.86.8 g/dL
Serum albumin: 3.53.5 g/dL
Total bilirubin: 2.12.1 mg/dL
Direct bilirubin: 0.80.8 mg/dL
Aspartate aminotransferase (AST): 185 U/L
Alanine aminotransferase (ALT): 210 U/L

Diagnostic paracentesis yields 1.5 L of straw-colored fluid. Ascitic fluid analysis reveals:
Albumin: 1.41.4 g/dL
Total protein: 2.92.9 g/dL
Neutrophils: 80/μL80 / \mu L

Based on the laboratory and clinical findings, which of the following is the most likely underlying mechanism for this patient's abdominal fluid accumulation?

Show answer & explanation

Answer: Hepatic venous outflow obstruction

Answer

The correct answer is hepatic venous outflow obstruction.
The correct answer is hepatic venous outflow obstruction. This patient's clinical presentation of aquagenic pruritus, ruddy complexion, and elevated hemoglobin, leukocytes, and platelets is highly indicative of polycythemia vera. Myeloproliferative disorders are major risk factors for atypical venous thromboses, including Budd-Chiari syndrome (hepatic vein thrombosis). To determine the etiology of ascites, the serum-ascites albumin gradient (SAAG) is calculated. This patient's SAAG is 3.5−1.4=2.13.5 - 1.4 = 2.1 g/dL. A SAAG ≥1.1\geq 1.1 g/dL demonstrates that portal hypertension is the driving force behind the fluid accumulation. Next, the ascitic fluid total protein must be evaluated to differentiate the cause of portal hypertension. An ascitic total protein ≥2.5\geq 2.5 g/dL indicates that the hepatic sinusoids are intact and allowing protein to leak, which points specifically to post-sinusoidal portal hypertension. Causes of post-sinusoidal portal hypertension include right ventricular failure, constrictive pericarditis, and Budd-Chiari syndrome. Because the patient's jugular venous pressure is normal (66 cm H2OH_2O) and there is no peripheral edema, cardiac etiologies are excluded, leaving hepatic venous outflow obstruction as the diagnosis.

Step-by-Step Solution

1
Calculate the serum-ascites albumin gradient (SAAG) by subtracting the ascitic fluid albumin from the serum albumin.
SAAG=3.5−1.4=2.1 g/dL\text{SAAG} = 3.5 - 1.4 = 2.1 \text{ g/dL}.
A SAAG ≥1.1\geq 1.1 g/dL confirms the presence of portal hypertension as the primary driver of the ascites.
2
Evaluate the ascitic fluid total protein.
Ascitic total protein is 2.92.9 g/dL (which is ≥2.5\geq 2.5 g/dL).
In the setting of portal hypertension, a high ascitic total protein (≥2.5\geq 2.5 g/dL) indicates intact hepatic sinusoids, localizing the pathology to a post-sinusoidal etiology (e.g., Budd-Chiari syndrome or right-sided heart failure).
3
Synthesize the laboratory interpretation with the clinical presentation.
The patient has signs of polycythemia vera (pruritus, panmyelosis) creating a hypercoagulable state, alongside a normal jugular venous pressure (66 cm H2OH_2O).
The normal jugular venous pressure rules out right-sided heart failure, making hepatic venous outflow obstruction (Budd-Chiari syndrome) the most likely diagnosis.

Key Concept

Ascitic fluid analysis using SAAG and total protein accurately localizes the etiology of ascites; a SAAG >= 1.1 g/dL with total protein >= 2.5 g/dL indicates post-sinusoidal portal hypertension.
Question 2607Question →

A 54-year-old woman is evaluated in the emergency department for a sudden-onset, agonizing headache that began 12 hours ago. She describes it as the most severe headache she has ever experienced, noting that it reached peak intensity within seconds. She also reports photophobia and nausea. Her medical history is notable for essential hypertension and a 20-pack-year smoking history. Vital signs show a blood pressure of 165/95 mmHg, pulse of 92/min, and respiratory rate of 16/min. Physical examination reveals photophobia and resistance to passive neck flexion. There are no focal motor or sensory deficits. A non-contrast head computed tomography (CT) scan is performed immediately and shows no evidence of intracranial hemorrhage or mass effect. Which of the following is the most appropriate next step in the diagnostic workup?

Show answer & explanation

Answer: Lumbar puncture

Answer

The most appropriate next step in the diagnostic workup is to perform a lumbar puncture to evaluate the cerebrospinal fluid for red blood cells or xanthochromia.
In a patient presenting with a classic 'thunderclap' headache and meningeal signs, the clinical suspicion for aneurysmal subarachnoid hemorrhage (SAH) is extremely high. The initial diagnostic test of choice is a non-contrast computed tomography (CT) scan of the head. While modern CT scanners are nearly 100% sensitive for detecting SAH if performed within 6 hours of symptom onset, this sensitivity decreases significantly as time passes because the subarachnoid blood is rapidly cleared and becomes isodense with the surrounding brain tissue. In this patient, the headache began 12 hours prior to evaluation. Therefore, a negative head CT does not definitively rule out the diagnosis. The standard of care mandates performing a lumbar puncture as the immediate sequential diagnostic step to analyze the cerebrospinal fluid for elevated red blood cell counts or xanthochromia (yellowish discoloration due to bilirubin from hemoglobin breakdown). Only after SAH is confirmed should the workup proceed to advanced vascular imaging to identify the source of bleeding.

Step-by-Step Solution

1
Evaluate the patient's clinical presentation and vital signs.
The patient presents with a 'thunderclap' headache and nuchal rigidity, establishing a very high pre-test probability for an acute subarachnoid hemorrhage.
To identify high-acuity life-threatening emergencies that dictate an aggressive and immediate diagnostic pathway.
2
Assess the results and timing of the initial screening diagnostic test.
The non-contrast head CT, performed 12 hours after symptom onset, is negative for hemorrhage.
To determine if the most rapid initial imaging test has confirmed or effectively ruled out the suspected diagnosis.
3
Determine the appropriate sequential test based on the time elapsed since symptom onset.
Because the head CT was performed more than 6 hours after onset, its sensitivity is significantly diminished, mandating a lumbar puncture to definitively rule out the hemorrhage.
To prevent premature closure and ensure a life-threatening diagnosis is not missed due to the known temporal limitations of the initial screening modality.

Key Concept

In patients with a high clinical suspicion for subarachnoid hemorrhage and a negative non-contrast head CT performed more than 6 hours after symptom onset, a lumbar puncture is the required next step in the diagnostic sequence.
Question 2608Question →

A 44-year-old woman is evaluated in the emergency department for severe, unremitting right upper quadrant abdominal pain that started 12 hours ago. The pain radiates to her right subscapular region and is associated with nausea and two episodes of bilious emesis. She has a history of diet-controlled type 2 diabetes mellitus and hyperlipidemia. Her temperature is 38.3°C (100.9°F), blood pressure is 135/85 mm Hg, pulse is 102/min, and respirations are 18/min. Physical examination demonstrates marked tenderness to palpation in the right upper quadrant with voluntary guarding, making deep palpation difficult. Laboratory results show:

TestValue
Leukocyte count14,500/mm³
Total bilirubin1.0 mg/dL
Alkaline phosphatase95 U/L
Aspartate aminotransferase (AST)32 U/L
Alanine aminotransferase (ALT)38 U/L
Amylase60 U/L

A transabdominal right upper quadrant ultrasound reveals multiple echogenic foci with posterior acoustic shadowing within the gallbladder. The gallbladder wall measures 2.5 mm in thickness, and there is no pericholecystic fluid. The common bile duct diameter is 4 mm. The sonographic Murphy sign cannot be definitively assessed due to the patient's guarding. The clinical suspicion for acute cholecystitis remains high.

Which of the following is the most appropriate next imaging study to establish the diagnosis?

Show answer & explanation

Answer: Hepatic iminodiacetic acid (HIDA) cholescintigraphy

Answer

Hepatic iminodiacetic acid (HIDA) cholescintigraphy
The correct answer is hepatic iminodiacetic acid (HIDA) cholescintigraphy. In patients presenting with a clinical picture highly suspicious for acute cholecystitis (e.g., severe right upper quadrant pain, fever, leukocytosis) who have an equivocal or non-diagnostic initial abdominal ultrasound, HIDA cholescintigraphy is the standard next step in diagnosis. While this patient's ultrasound demonstrated gallstones, it lacked definitive features of acute inflammation (such as a thickened gallbladder wall or pericholecystic fluid), and the sonographic Murphy sign could not be reliably assessed due to voluntary guarding. A HIDA scan involves the intravenous injection of a radiotracer that is taken up by the liver and excreted into the biliary tree. In acute cholecystitis, the cystic duct is typically obstructed by a gallstone, preventing the radiotracer from entering the gallbladder. Thus, non-visualization of the gallbladder on cholescintigraphy confirms the diagnosis of acute cholecystitis.

Step-by-Step Solution

1
Analyze the clinical presentation and laboratory findings.
The patient has systemic signs of inflammation (fever, leukocytosis) and localized right upper quadrant pain, highly suggestive of acute cholecystitis. Normal liver chemistries and amylase lower the likelihood of choledocholithiasis or acute pancreatitis.
To establish the pretest probability of acute cholecystitis and rule out immediate alternate biliary pathologies.
2
Evaluate the findings of the initial right upper quadrant ultrasonography.
The ultrasound confirms cholelithiasis but lacks definitive secondary signs of acute cholecystitis (wall thickening >4 mm, pericholecystic fluid). The sonographic Murphy sign is indeterminate.
To determine if the primary diagnostic modality confirms the suspected diagnosis.
3
Determine the most appropriate next diagnostic step for high clinical suspicion with an equivocal ultrasound.
A HIDA scan is selected to directly evaluate cystic duct patency and confirm the diagnosis.
Because cholescintigraphy is highly sensitive and specific for acute cholecystitis when initial ultrasonography is non-diagnostic.

Key Concept

In patients with a high clinical suspicion for acute cholecystitis but equivocal findings on initial right upper quadrant ultrasonography, hepatic iminodiacetic acid (HIDA) cholescintigraphy is the most appropriate next imaging study to confirm the diagnosis.
Question 2609Question →

A 65-year-old African American man comes to the clinic for follow-up of heart failure. He was hospitalized 4 weeks ago for acute decompensated heart failure, and an echocardiogram at that time showed a left ventricular ejection fraction of 30%. His past medical history includes type 2 diabetes mellitus, hyperlipidemia, and bilateral renal artery stenosis that was diagnosed via magnetic resonance angiography two years ago. His current medications include carvedilol, furosemide, and atorvastatin. His blood pressure is 146/92 mm Hg and his pulse is 68/min. Physical examination shows a regular heart rate, clear lungs to auscultation, and no peripheral edema.

Laboratory studies reveal a serum sodium of 138 mEq/L, serum potassium of 4.2 mEq/L, blood urea nitrogen of 18 mg/dL, and serum creatinine of 1.1 mg/dL.

The physician discusses initiating an additional medication to optimize his guideline-directed medical therapy. Which of the following medications is absolutely contraindicated in this patient?

Show answer & explanation

Answer: Lisinopril

Answer

Lisinopril is absolutely contraindicated in this patient.
Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor. In patients with bilateral renal artery stenosis, renal perfusion is chronically compromised. The kidneys compensate by upregulating the renin-angiotensin-aldosterone system (RAAS). Angiotensin II preferentially constricts the efferent arteriole, which helps maintain intraglomerular pressure and the glomerular filtration rate (GFR). Administering an ACE inhibitor abruptly removes this compensatory efferent vasoconstriction, leading to a precipitous drop in GFR and potentially irreversible acute renal failure. Therefore, ACE inhibitors and angiotensin II receptor blockers (ARBs) are absolutely contraindicated in these patients. For this patient, the combination of hydralazine and isosorbide dinitrate would be the preferred alternative for afterload and preload reduction to improve long-term survival.

Step-by-Step Solution

1
Identify the patient's primary condition and treatment goal.
The patient has heart failure with reduced ejection fraction (HFrEF) and requires optimization of guideline-directed medical therapy.
To determine which drug classes are typically indicated for improving survival.
2
Analyze the patient's comorbidities for potential absolute contraindications.
The patient has a known history of bilateral renal artery stenosis.
Comorbidities heavily influence medication safety profiles, particularly in heart failure management where therapies often affect renal hemodynamics.
3
Evaluate each medication option against the identified comorbidity.
Lisinopril (an ACE inhibitor) blocks angiotensin II, which is required to maintain glomerular filtration rate in the setting of bilateral renal artery stenosis.
To isolate the medication that is strictly contraindicated and could cause severe patient harm.

Key Concept

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are absolutely contraindicated in patients with bilateral renal artery stenosis due to the risk of precipitating acute renal failure.
Question 2610Question →

A 31-year-old woman is brought to the emergency department by paramedics due to continuous seizure activity. Her husband states she has a history of epilepsy but ran out of her medications two days ago. He reports the generalized tonic-clonic movements began approximately 10 minutes prior to EMS arrival and have not ceased. She is actively seizing on the stretcher. Vital signs include a blood pressure of 145/92 mm Hg, heart rate of 122/min, respiratory rate of 22/min, and oxygen saturation of 91% on room air. Point-of-care blood glucose is 98 mg/dL. Two large-bore peripheral intravenous catheters are successfully placed by the nursing staff immediately upon arrival.

Assuming the patient's seizures remain refractory to each successive intervention, arrange the following management steps in the most appropriate chronological sequence for her stabilization and definitive care.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence for status epilepticus stabilization is: 1) Airway positioning and oxygenation, 2) First-line abortive therapy with IV lorazepam, 3) Second-line maintenance loading with IV fosphenytoin, 4) Escalation to intubation and continuous anesthetic infusion (propofol) for refractory cases, and 5) ICU transfer for continuous EEG monitoring.
Status epilepticus is a neurologic emergency requiring a strict, time-dependent protocol. Step 1 is always basic stabilization (airway protection, lateral positioning, oxygenation, and checking blood glucose). Step 2 utilizes IV lorazepam (or midazolam/diazepam) as the fastest means to halt seizure activity. Step 3 introduces a long-acting agent like fosphenytoin to prevent recurrence or treat continued activity. Step 4 is reserved for refractory cases, requiring induction of a pharmacologic coma with propofol or midazolam, which mandates preceding or concurrent endotracheal intubation. Step 5 completes the pathway; once physical movement is suppressed by coma-inducing agents, continuous EEG is the only reliable way to confirm the cessation of pathological brain activity.

Step-by-Step Solution

1
Address Airway, Breathing, and Circulation (ABCs).
The patient is positioned laterally and provided with supplemental oxygen.
This establishes physical stabilization, minimizes the immediate risk of aspiration of oral secretions or vomitus, and mitigates hypoxemia before pharmacologic intervention.
2
Administer first-line medical therapy for active seizures.
Intravenous lorazepam is pushed.
Benzodiazepines rapidly cross the blood-brain barrier to potentiate GABA receptors, making them the fastest and most effective first step to abort status epilepticus.
3
Administer second-line antiepileptic therapy.
Intravenous fosphenytoin (or levetiracetam/valproic acid) is administered as a loading dose.
Because the effects of benzodiazepines are short-lived, a long-acting antiepileptic drug is required to establish a sustained elevation of the seizure threshold, especially when first-line therapy fails.
4
Escalate to refractory status epilepticus management.
The patient undergoes rapid sequence intubation and a continuous propofol infusion is started.
When seizures resist initial therapies, medically induced coma with continuous anesthetics is required to halt excitotoxicity. Intubation is necessary at this stage to protect the airway against the profound respiratory depression caused by these agents.
5
Initiate post-stabilization monitoring.
The patient is transferred to the ICU and connected to continuous EEG.
Paralytics and anesthetic agents mask the physical manifestations of seizures. Continuous EEG is necessary to confirm that electrographic seizure activity has successfully ceased (burst suppression).

Key Concept

The sequential management of status epilepticus progresses strictly from basic life support (ABCs), to rapid-acting benzodiazepines (0-20 min), to longer-acting antiepileptic drugs (20-40 min), to continuous anesthetic infusions with intubation (>40 min), concluding with continuous EEG monitoring.
Question 2611Question →

A 41-year-old man is brought to the emergency department by ambulance after being found obtunded in an alleyway. Medical records indicate a history of severe alcohol use disorder and major depressive disorder. Vital signs are temperature 36.1°C (97.0°F), blood pressure 105/65 mm Hg, pulse 112/min, and respirations 24/min. Physical examination shows a somnolent man who arouses only to painful stimuli. Pupils are equal and reactive. Cardiopulmonary examination is unremarkable.

Laboratory results are as follows:

TestResultReference Range
Sodium138 mEq/L136-145 mEq/L
Potassium4.8 mEq/L3.5-5.0 mEq/L
Chloride100 mEq/L95-105 mEq/L
Bicarbonate14 mEq/L22-28 mEq/L
Blood urea nitrogen14 mg/dL7-18 mg/dL
Creatinine1.3 mg/dL0.6-1.2 mg/dL
Glucose90 mg/dL70-110 mg/dL
Ethanol138 mg/dL0 mg/dL
Serum osmolality (measured)345 mOsm/kg H2O275-295 mOsm/kg H2O

Arterial blood gas analysis on room air reveals:
pH: 7.23
PaCO2: 28 mm Hg
PaO2: 96 mm Hg

Based on the laboratory results provided, calculate the patient's osmolar gap.

Show answer & explanation

Answer: 29

Answer

29
The osmolar gap is the difference between the directly measured serum osmolality and the calculated serum osmolality. When evaluating a patient for toxic alcohol ingestion, any known ethanol must be included in the calculation to isolate the gap caused specifically by unmeasured toxins like methanol or ethylene glycol. The standard formula using US units (mg/dL) is: Calculated Osmolality = 2[Na+]+Glucose18+BUN2.8+Ethanol4.62[\text{Na}^+] + \frac{\text{Glucose}}{18} + \frac{\text{BUN}}{2.8} + \frac{\text{Ethanol}}{4.6}. Using the provided laboratory values, this equals 2(138)+9018+142.8+1384.6=276+5+5+30=316 mOsm/kg H2O2(138) + \frac{90}{18} + \frac{14}{2.8} + \frac{138}{4.6} = 276 + 5 + 5 + 30 = 316 \text{ mOsm/kg H}_2\text{O}. Subtracting this calculated value from the measured osmolality of 345 yields an osmolar gap of 29 mOsm/kg H2O29 \text{ mOsm/kg H}_2\text{O}. An osmolar gap greater than 10-15 is generally considered abnormal and highly suggestive of an unmeasured alcohol.

Step-by-Step Solution

1
Determine the indication for calculating the osmolar gap.
The patient has an elevated anion gap (138−(100+14)=24138 - (100 + 14) = 24) and a history of substance abuse, raising suspicion for toxic alcohol ingestion.
An unexplained high anion gap metabolic acidosis requires calculation of the osmolar gap to identify hidden osmotically active substances.
2
Calculate the theoretical serum osmolality using the standard formula.
2(138)+9018+142.8+1384.6=276+5+5+30=316 mOsm/kg H2O2(138) + \frac{90}{18} + \frac{14}{2.8} + \frac{138}{4.6} = 276 + 5 + 5 + 30 = 316 \text{ mOsm/kg H}_2\text{O}.
This formula accounts for the primary solutes in the blood, including ethanol, which is known to be present in this patient.
3
Determine the osmolar gap.
Measured osmolality (345) - Calculated osmolality (316) = 29 mOsm/kg H2O29 \text{ mOsm/kg H}_2\text{O}.
The difference between measured and calculated osmolality reveals the concentration of unmeasured osmotically active agents.

Key Concept

Calculation and interpretation of the osmolar gap in the presence of ethanol.
Question 2612Question →

A 58-year-old male is evaluated in the ambulatory neurology clinic for progressive walking difficulty, which he notes is severely exacerbated in dimly lit environments. Over the past six months, he has also experienced sudden, intense, "electric shock-like" pains shooting down both legs. His medical history is notable only for a painless genital sore in his twenties that healed spontaneously without treatment. On examination, he demonstrates a wide-based, stomping gait. When instructed to stand with his feet approximated and arms outstretched, he remains stable with his eyes open; however, upon closing his eyes, he sways dramatically and requires assistance to prevent a fall. Deep tendon reflexes cannot be elicited at the knees or ankles. Perception of tuning fork vibration and joint position is profoundly impaired in the distal lower extremities. Muscle strength is graded as 5/55/5 globally.

Further physical examination of this patient's eyes is most likely to reveal which of the following pupillary abnormalities?

Show answer & explanation

Answer: Bilaterally small, irregular pupils that constrict to near targets but do not react to direct light

Answer

The patient most likely has bilaterally small, irregular pupils that constrict to near targets but do not react to direct light (Argyll Robertson pupils).
The correct answer describes Argyll Robertson pupils, which are highly specific for neurosyphilis. The patient's clinical presentation—sensory ataxia (manifested by falls in the dark and a positive Romberg sign), absent lower extremity reflexes, impaired proprioception, and lancinating 'lightning' pains—is the classic tetrad of tabes dorsalis. This is a form of tertiary neurosyphilis caused by Treponema pallidum infection that preferentially damages the dorsal columns and dorsal roots of the spinal cord. The history of a painless genital ulcer decades prior is pathognomonic for a primary syphilitic chancre. Argyll Robertson pupils are bilaterally small and accommodate (constrict to near vision) but do not react to direct light due to bilateral lesions in the pretectal nuclei.

Step-by-Step Solution

1
Analyze the gait and sensory findings
The patient has a positive Romberg sign, impaired proprioception/vibration, and a wide-based gait, indicating sensory ataxia localizing to the dorsal columns.
Differentiating sensory ataxia from cerebellar ataxia is critical; a positive Romberg sign confirms a proprioceptive, rather than cerebellar, deficit.
2
Integrate the reflex findings and pain history
Absent lower extremity reflexes and 'electric shock-like' (lightning) pains indicate involvement of the dorsal nerve roots.
The combination of dorsal column and dorsal root degeneration is the pathologic hallmark of tabes dorsalis.
3
Correlate with the patient's medical history
The history of a spontaneously healing, painless genital sore decades ago strongly suggests an untreated primary syphilis infection (chancre).
Tertiary neurosyphilis often presents decades after the primary infection.
4
Identify the expected associated physical exam finding
Tabes dorsalis is classically associated with Argyll Robertson pupils, which exhibit light-near dissociation.
Identifying the eponymous pupillary sign solidifies the clinical diagnosis of neurosyphilis.

Key Concept

Tabes dorsalis (tertiary neurosyphilis) presents with posterior column degeneration (sensory ataxia, positive Romberg sign) and dorsal root damage (areflexia, lightning pains), and is classically associated with Argyll Robertson pupils (light-near dissociation).
Question 2613Question →

During a shift in the emergency department, a physician evaluates an elderly female patient residing in a skilled nursing facility. The patient was transported for acute medical assessment due to a 72-hour history of obstipation, progressive abdominal distention, and frequent bilious emesis. Chart review notes a long-standing history of symptomatic gallstones that were managed expectantly due to high surgical risk. Currently, the patient is tachycardic and hypotensive with dry mucous membranes. Abdominal auscultation reveals high-pitched, tinkling bowel sounds over a distended, tympanic abdomen. The physician orders an acute abdominal plain radiograph series. The radiologist's read reports markedly distended jejunal and ileal loops with step-ladder air-fluid levels and an absence of colonic gas. Furthermore, there is a distinct branching tubular lucency over the hepatic silhouette and a 3.5-centimeter target-like radiopaque structure situated near the ileocecal valve. Based on the integration of these radiologic findings, which of the following best describes the fundamental pathophysiologic event that precipitated this condition?

Show answer & explanation

Answer: Formation of a fistulous tract between the inflamed gallbladder and the adjacent small intestine

Answer

The correct pathophysiologic mechanism is the formation of a fistulous tract between the inflamed gallbladder and the adjacent small intestine (cholecystoenteric fistula).
The correct answer identifies the underlying mechanism of gallstone ileus. Chronic cholecystitis leads to inflammation and adhesion between the gallbladder and the adjacent gastrointestinal tract (most commonly the duodenum). This can result in necrosis and the formation of a cholecystoenteric fistula. A large gallstone can then pass directly into the small intestine. It travels distally until it impacts at the narrowest portion of the bowel, typically the terminal ileum or ileocecal valve, causing a mechanical small bowel obstruction. The fistulous tract also allows intestinal gas to retrogradely enter the biliary tree, presenting as pneumobilia (central branching lucency over the liver). This classic combination of small bowel obstruction, pneumobilia, and an ectopic gallstone on imaging is known as Rigler's triad.

Step-by-Step Solution

1
Analyze the patient's clinical presentation.
The patient exhibits classic signs of a mechanical small bowel obstruction, including obstipation, bilious emesis, abdominal distension, and high-pitched, tinkling bowel sounds.
To establish the primary clinical syndrome requiring investigation.
2
Evaluate the specific radiographic findings provided.
The imaging demonstrates small bowel obstruction (step-ladder air-fluid levels), pneumobilia (branching lucency over the liver), and an ectopic gallstone (radiopaque structure near the ileocecal valve).
To identify key diagnostic clues that narrow the differential diagnosis for the bowel obstruction.
3
Synthesize the findings to determine the underlying pathophysiology.
The combination of these three radiologic findings is known as Rigler's triad, which is pathognomonic for gallstone ileus. This condition occurs when a fistula forms between the gallbladder and bowel.
To answer the specific question asking for the precipitating pathophysiologic event.

Key Concept

Rigler's triad on abdominal radiography (mechanical small bowel obstruction, pneumobilia, and an ectopic gallstone) is pathognomonic for gallstone ileus, which occurs secondary to a cholecystoenteric fistula.
Question 2614Question →

A 76-year-old man is brought to the outpatient continuity clinic by his son due to a 6-month history of worsening memory and episodic confusion. The son reports that the patient frequently misplaces household items, struggles to recall the names of familiar acquaintances, and recently became disoriented while driving to his local grocery store. Medical history is notable for hypertension, benign prostatic hyperplasia, and osteoarthritis of the right knee. Surgical history includes an uncomplicated appendectomy in his twenties. He lives alone, does not smoke, and consumes one glass of wine weekly. Current medications include amlodipine, tamsulosin, and over-the-counter diphenhydramine, which he began taking nightly about seven months ago for insomnia. He also takes acetaminophen as needed for joint pain. The physician is conducting a targeted medical history to evaluate the etiology of the cognitive decline. Which of the following elements of the history are critical to prioritize? (Select all that apply)

Select all that apply

Show answer & explanation

Answer: The chronological relationship between the onset of cognitive changes and the initiation of the nightly sleep aid; The trajectory of symptom progression, specifically assessing whether the decline has been steady or step-wise

Answer

The critical historical elements to prioritize are evaluating the temporal relationship between cognitive changes and the use of the over-the-counter sleep aid, and assessing whether the trajectory of the cognitive decline has been gradual or step-wise.
When evaluating new-onset cognitive decline in an older adult, obtaining a history that purposefully distinguishes between reversible and irreversible causes is paramount. Assessing the temporal relationship between the onset of symptoms and the initiation of strongly anticholinergic medications, such as diphenhydramine, is essential for identifying medication-induced cognitive impairment. Additionally, establishing the trajectory of the decline helps differentiate vascular dementia (characterized by a step-wise progression) from primary neurodegenerative processes like Alzheimer disease (characterized by an insidious, steady decline). Both of these elements directly inform the subsequent diagnostic and management steps.

Step-by-Step Solution

1
Analyze the patient's presentation and medication list.
The patient is an older adult presenting with a 6-month history of cognitive decline who recently started taking diphenhydramine.
Identifying new medications, especially over-the-counter supplements and sleep aids, highlights potential pharmacological triggers for delirium or reversible dementia.
2
Determine the highest priority goals for the initial medical history evaluation of cognitive decline.
The history must prioritize ruling out reversible etiologies (such as medication side effects) and characterizing the progression of the disease.
Reversible causes must be addressed before assigning a diagnosis of an irreversible neurodegenerative disorder.
3
Differentiate between the roles of the relevant historical findings.
The chronological relationship of medication use points toward a reversible cause, while assessing for a step-wise versus steady decline differentiates vascular from neurodegenerative dementia.
Both elements directly guide the immediate diagnostic differential and management plan, unlike incidental lab findings or complex genetic pedigrees.

Key Concept

Targeted History in Cognitive Decline
Question 2615Question →

While doing yard work, a 65-year-old man experiences a sudden onset of severe dyspnea, dizziness, and a diffuse rash. His wife immediately drives him to the nearest emergency room. The patient has a known past medical history of a myocardial infarction two years prior, as well as hypertension and type 2 diabetes mellitus. His prescribed medications include aspirin, metoprolol, lisinopril, and metformin.

Upon arrival at the triage desk, he appears extremely restless, is profusely diaphoretic, and can only speak in one-word gasps.

Vital signs reveal a temperature of 37.1°C (98.8°F), blood pressure of 78/42 mmHg, heart rate of 134/min, respiratory rate of 28/min, and oxygen saturation of 89% on ambient air.

Physical examination demonstrates significant periorbital swelling and widespread raised, erythematous plaques across his torso and limbs. Auscultation of the lungs reveals prominent bilateral expiratory wheezing.

Which of the following represents the most appropriate immediate next step in stabilizing this patient?

Show answer & explanation

Answer: Inject epinephrine intramuscularly into the anterolateral thigh

Answer

The correct answer is to inject epinephrine intramuscularly into the anterolateral thigh.
This patient is presenting with anaphylactic shock, likely triggered by an insect sting while doing yard work. The diagnosis is clinical, characterized by the acute onset of respiratory compromise (hypoxia, wheezing) and cardiovascular collapse (severe hypotension, tachycardia), accompanied by characteristic mucocutaneous involvement (periorbital edema, urticaria). The single most appropriate and urgent initial step in the stabilization of a patient with anaphylaxis is the administration of intramuscular epinephrine into the anterolateral thigh. Epinephrine's alpha-1 agonist effects counteract vasodilation and increase blood pressure, while its beta-2 agonist effects promote bronchodilation and inhibit further release of inflammatory mediators from mast cells and basophils. There are no absolute contraindications to intramuscular epinephrine administration in the setting of anaphylaxis—even in a patient with a history of myocardial infarction—because untreated anaphylactic shock is rapidly fatal.

Step-by-Step Solution

1
Identify the underlying clinical syndrome causing the patient's instability.
The patient is experiencing anaphylactic shock.
The sudden onset of severe dyspnea, hypotension, wheezing, and an urticarial rash following outdoor exposure (likely an insect sting) is the classic presentation of a severe systemic allergic reaction.
2
Determine the highest-priority life-saving intervention.
Immediate administration of intramuscular epinephrine is required.
Epinephrine is the only first-line medication capable of reversing the severe vasodilation, vascular permeability, and bronchoconstriction of anaphylaxis. It must be administered before any diagnostic testing or secondary treatments.

Key Concept

Immediate administration of intramuscular epinephrine is the primary, life-saving intervention for anaphylactic shock, and should never be delayed by diagnostic testing, subspecialty consultations, or the administration of secondary adjunctive medications.
Question 2616Question →

A 65-year-old man presents to the emergency department with a 2-day history of progressively worsening dyspnea, orthopnea, and a cough productive of pink, frothy sputum. He has a past medical history of an anterior myocardial infarction three years ago, subsequent heart failure with reduced ejection fraction, and essential hypertension. His home medications include oral lisinopril, carvedilol, and low-dose aspirin. Upon arrival, his temperature is 37.0°C (98.6°F), blood pressure is 155/90 mm Hg, pulse is 112/min, and respiratory rate is 26/min. Pulse oximetry shows an oxygen saturation of 88% on room air. Physical examination reveals elevated jugular venous pressure, an S3 gallop, and diffuse bilateral crackles on lung auscultation. An electrocardiogram shows sinus tachycardia without acute ST-segment or T-wave changes. Which of the following is the most appropriate immediate pharmacologic intervention?

Show answer & explanation

Answer: Intravenous furosemide

Answer

Intravenous furosemide
The correct intervention is intravenous furosemide. This patient is presenting with classic signs of acute decompensated heart failure (ADHF) complicated by pulmonary edema, as evidenced by his progressive dyspnea, frothy sputum, hypoxia, elevated jugular venous pressure, S3 gallop, and diffuse crackles. The immediate priority in managing ADHF with volume overload is to reduce ventricular preload and alleviate pulmonary congestion. Intravenous loop diuretics, such as furosemide, are the first-line pharmacologic intervention for this purpose. They act quickly to induce diuresis and also have an early venodilatory effect that reduces venous return to the heart even before the onset of significant urine output.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and physical exam findings.
The patient presents with severe dyspnea, hypoxia, frothy sputum, elevated jugular venous pressure, an S3 gallop, and bilateral crackles.
To establish the primary diagnosis of acute decompensated heart failure (ADHF) with pulmonary edema.
2
Evaluate the patient's most urgent physiological derangement.
The patient is severely volume overloaded and hypoxic, requiring rapid diuresis and reduction of pulmonary fluid.
To guide the immediate stabilization of the patient's respiratory and hemodynamic status.
3
Select the appropriate pharmacologic agent for initial stabilization.
Intravenous furosemide is selected as the primary intervention.
Loop diuretics rapidly decrease intravascular volume and venous return (preload), effectively relieving acute pulmonary edema.

Key Concept

First-line pharmacologic management of acute decompensated heart failure with pulmonary edema.
Estimated Time:1m 0s
Question 2617Question →

A physician is reviewing the charts of four newly admitted patients with complex multisystem presentations. Match each patient's clinical scenario with the most appropriate targeted laboratory investigation to establish the underlying diagnosis.

Click a left item, then click its matching right item

Items

A 45-year-old individual presents with recent onset of hemoptysis, rapidly progressive acute kidney injury, and ulceration of the nasal septum.
A 55-year-old patient with chronic, untreated Hepatitis C infection develops palpable purpura on the lower extremities, severe joint pain, and an acute decline in renal function.
A 25-year-old individual with a history of three consecutive first-trimester miscarriages presents with an unprovoked deep vein thrombosis and a paradoxically prolonged activated partial thromboplastin time (aPTT).
A 60-year-old patient reports severe, unrelenting lower back pain and is found to have a normocytic anemia, hypercalcemia, and an elevated serum creatinine.

Matches

Show answer & explanation

Answer

The patient with hemoptysis and nasal ulcers requires ANCA testing. The Hepatitis C patient with purpura requires serum cryoglobulin testing. The patient with recurrent miscarriages and DVT requires an antiphospholipid antibody panel. The older patient with back pain, anemia, and hypercalcemia requires serum protein electrophoresis and free light chain testing.
Each patient presentation is a classic description of a multisystem disease requiring specific initial laboratory testing. Granulomatosis with polyangiitis requires ANCA. Mixed cryoglobulinemia secondary to Hepatitis C requires cryoglobulin testing. Antiphospholipid syndrome necessitates a specific antibody panel. Multiple myeloma requires SPEP and free light chains.

Step-by-Step Solution

1
Evaluate the clinical presentation of the 45-year-old with hemoptysis, rapid acute kidney injury, and nasal ulcers.
The combination suggests a pulmonary-renal syndrome with upper airway involvement, which is a classic triad for Granulomatosis with polyangiitis (GPA).
Identifying the underlying syndromic pattern is required to select the targeted diagnostic autoantibody test (ANCA).
2
Analyze the symptoms of the 55-year-old with Hepatitis C, palpable purpura, joint pain, and kidney injury.
These findings represent the classic triad of mixed cryoglobulinemia syndrome, a known complication of chronic Hepatitis C.
Recognizing the association between Hepatitis C and this specific vasculitis directs the clinician to order serum cryoglobulins.
3
Assess the 25-year-old with recurrent miscarriages, unprovoked DVT, and a prolonged aPTT.
This history indicates a hypercoagulable state. The paradoxically prolonged aPTT in vitro suggests the presence of a lupus anticoagulant.
A prolonged aPTT with a history of thrombosis (rather than bleeding) is pathognomonic for Antiphospholipid syndrome, necessitating a specific antibody panel.
4
Review the presentation of the 60-year-old with back pain, normocytic anemia, hypercalcemia, and renal dysfunction.
These elements form the 'CRAB' criteria (hyperCalcemia, Renal involvement, Anemia, Bone lesions) characteristic of symptomatic multiple myeloma.
Identifying the CRAB criteria prompts the ordering of a serum protein electrophoresis and free light chain assay to look for a monoclonal protein spike.

Key Concept

Targeted laboratory testing must be guided by pattern recognition of classic multisystem clinical syndromes.
Question 2618Question →

A 65-year-old woman presents to the outpatient clinic with a 3-week history of painless yellowing of her skin and eyes. She also reports a 5-kg (11-lb) unintentional weight loss, dark urine, and pale acholic stools. She has no significant past medical history. Vital signs are within normal limits. Physical examination reveals profound scleral icterus and a palpable, non-tender mass in the right upper quadrant. Laboratory studies show a total bilirubin of 10.2 mg/dL, direct bilirubin of 8.6 mg/dL, and an alkaline phosphatase of 750 U/L. A multidisciplinary tumor board anticipates she will require neoadjuvant chemotherapy followed by surgical resection, but notes that she is currently suffering from severe, intractable pruritus due to hyperbilirubinemia.

Arrange the following diagnostic and interventional modalities in the most appropriate chronological sequence for the evaluation and management of this patient, from the initial diagnostic step to the final therapeutic step.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Transabdominal right upper quadrant ultrasonography, 2) Pancreatic protocol multiphasic computed tomography, 3) Endoscopic ultrasonography with fine-needle aspiration, 4) Endoscopic retrograde cholangiopancreatography with biliary stenting.
The patient's painless jaundice, weight loss, and Courvoisier sign (palpable, non-tender gallbladder) strongly suggest a periampullary malignancy, most likely pancreatic adenocarcinoma. The evidence-based sequencing of modalities minimizes patient risk and maximizes diagnostic yield. Transabdominal ultrasound is universally the first step to confirm ductal dilation. Once confirmed, a multiphasic pancreatic protocol CT is required to stage the tumor and determine surgical resectability. Crucially, this CT must be done before any invasive procedures like ERCP, as biliary stents cause artifact, and introduced air obscures vital vascular anatomy. After staging is complete, EUS is the preferred modality to obtain a tissue biopsy (FNA) without the risk of peritoneal seeding associated with percutaneous biopsies. Finally, because the patient has intractable pruritus and is slated for neoadjuvant chemotherapy (meaning a delay before definitive surgical resection), ERCP with biliary stenting is performed to relieve the obstruction.

Step-by-Step Solution

1
Order transabdominal right upper quadrant ultrasonography.
Confirms intra- and extrahepatic biliary ductal dilation and the absence of radiopaque gallstones in the gallbladder.
Ultrasound is the highly sensitive, cost-effective, and non-invasive initial test of choice to evaluate painless jaundice and confirm an obstructive etiology.
2
Order a pancreatic protocol multiphasic computed tomography (CT) of the abdomen.
Identifies a suspected pancreatic head mass, evaluates for superior mesenteric artery or vein encasement, and screens for hepatic metastases.
Cross-sectional imaging must be performed prior to any invasive ductal manipulation (which can introduce air or alter tissue planes) to accurately stage the disease for resectability.
3
Perform endoscopic ultrasonography (EUS) with fine-needle aspiration (FNA).
Obtains a targeted tissue sample for histologic or cytologic analysis.
A definitive tissue diagnosis is required before initiating the planned neoadjuvant chemotherapy for pancreatic adenocarcinoma.
4
Perform endoscopic retrograde cholangiopancreatography (ERCP) with biliary stenting.
Decompresses the obstructed biliary tree, lowering serum bilirubin levels.
Therapeutic decompression is indicated because the patient has severe, intractable pruritus and requires neoadjuvant therapy prior to definitive surgical resection.

Key Concept

The diagnostic algorithm for suspected malignant biliary obstruction requires non-invasive confirmation (ultrasound), anatomic staging (multiphasic CT), tissue diagnosis (EUS-FNA), and finally therapeutic intervention (ERCP) if indicated for severe symptoms or delayed surgery.
Estimated Time:2m 0s
Question 2619Question →

Match each patient scenario involving the evaluation of suspected or confirmed Cushing syndrome with the most appropriate next step in their diagnostic workup.

Click a left item, then click its matching right item

Items

A 4242-year-old woman presents with recent central weight gain, violaceous striae, and proximal muscle weakness. No endocrinologic testing has been performed.
A 3838-year-old man has confirmed hypercortisolism based on two abnormal screening tests. His morning plasma adrenocorticotropic hormone (ACTH) level is undetectable (<5< 5 pg/mL).
A 4545-year-old woman has confirmed hypercortisolism and an elevated morning plasma ACTH level (6565 pg/mL). Following an 88-mg high-dose dexamethasone suppression test, her serum cortisol level decreases by 80%80\% from baseline.
A 5555-year-old man with a 3030-pack-year smoking history has confirmed hypercortisolism and a markedly elevated plasma ACTH level (150150 pg/mL). A high-dose dexamethasone suppression test shows no significant reduction in serum cortisol levels.

Matches

Show answer & explanation

Answer

The correct matches follow the established sequence: screen for hypercortisolism first (24-hour urine/low-dose dexamethasone), identify ACTH dependence for confirmed cases (Adrenal CT if suppressed ACTH), and use high-dose dexamethasone to differentiate ACTH-dependent sources (Pituitary MRI if suppressed, Chest/Abdomen CT if not suppressed).
The correct pairings align with standard endocrine guidelines for evaluating Cushing syndrome, which enforce a strict sequence: confirm excess cortisol production biochemically, measure ACTH to distinguish adrenal from central/ectopic sources, and use high-dose suppression testing to isolate ACTH-dependent pathologies before ordering any targeted imaging.

Step-by-Step Solution

1
Determine if hypercortisolism has been biochemically confirmed.
Patients without prior testing require initial screening with a 24-hour urine free cortisol, late-night salivary cortisol, or 1-mg dexamethasone suppression test.
Clinical signs alone are insufficient to diagnose Cushing syndrome, and premature anatomic imaging can detect clinically irrelevant incidentalomas.
2
Analyze the ACTH level in patients with confirmed hypercortisolism.
A suppressed ACTH level indicates an adrenal source (ACTH-independent), prompting an adrenal CT scan.
High cortisol levels normally suppress pituitary ACTH production; if ACTH is suppressed, the adrenal gland is autonomously producing cortisol.
3
Interpret the high-dose dexamethasone suppression test for patients with elevated ACTH.
Significant suppression (e.g., >50% reduction) points to a pituitary source, requiring a pituitary MRI. Lack of suppression points to an ectopic source, requiring a chest and abdominal CT.
Pituitary adenomas (Cushing disease) retain a partial negative feedback response to high-dose glucocorticoids, whereas ectopic ACTH-producing tumors typically do not respond to feedback.

Key Concept

Diagnostic algorithm for Cushing syndrome: Biochemical confirmation, followed by ACTH measurement, and targeted functional testing (high-dose dexamethasone) before appropriate anatomic imaging.
Estimated Time:1m 30s
Question 2620Question →

A 58-year-old man presents to the primary care clinic reporting a 9-month history of progressive fatigue, decreased libido, and erectile dysfunction. He has no headaches, visual changes, or prior testicular trauma. His vital signs show a blood pressure of 128/82 mmHg128/82 \text{ mmHg}, heart rate of 74 /min74 \text{ /min}, and respiratory rate of 14 /min14 \text{ /min}. His body mass index (BMI) is 34 kg/m234 \text{ kg/m}^2. Physical examination reveals normal visual fields, no gynecomastia, and bilaterally descended testes with a slightly soft consistency and a volume of 12 mL12 \text{ mL} bilaterally (normal: 15−25 mL15-25 \text{ mL}). The physician suspects male hypogonadism and initiates a stepwise laboratory evaluation.

Based on Endocrine Society guidelines, arrange the following laboratory investigations in the most appropriate chronological sequence for establishing the diagnosis and etiology. Assume each subsequent test is pursued only after the preceding test results confirm the need for further evaluation.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of laboratory testing is: Initial morning total testosterone → Confirmatory morning total and free testosterone → LH and FSH levels → Prolactin and iron studies.
The Endocrine Society guidelines mandate a strict stepwise approach to avoid over-testing and misdiagnosis. First, a single morning total testosterone is drawn for screening. If low, it must be confirmed on a different morning; in obese patients, free testosterone should also be measured due to likely suppressed SHBG. Only after confirming biochemical hypogonadism should LH and FSH be ordered to classify the condition as primary or secondary. Finally, if secondary hypogonadism is identified, etiologic tests like prolactin and iron studies are ordered prior to considering a pituitary MRI.

Step-by-Step Solution

1
Determine the initial screening test for hypogonadism.
Measurement of a single 8:00 AM fasting total serum testosterone level.
Testosterone exhibits a strong diurnal rhythm, peaking in the morning. A fasting morning sample is the most sensitive initial screen.
2
Identify the required confirmatory step after an initially low result.
Measurement of a repeat morning total serum testosterone along with a free testosterone level.
Testosterone levels can fluctuate due to acute illness or sleep variations. Guidelines require a second confirmatory morning value. Furthermore, obesity lowers Sex Hormone-Binding Globulin (SHBG), meaning total testosterone might be falsely low while free (active) testosterone remains normal. Thus, a free testosterone level is necessary for confirmation in this obese patient.
3
Select the test needed to localize the defect (primary vs. secondary).
Measurement of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels.
Once hypogonadism is biochemically confirmed, gonadotropins must be assessed. Elevated LH/FSH indicates primary testicular failure, whereas low/normal LH/FSH indicates a secondary (central) defect.
4
Determine the follow-up laboratory evaluation for secondary hypogonadism.
Measurement of serum prolactin and transferrin saturation.
If central hypogonadism is confirmed, secondary causes such as hyperprolactinemia (prolactinoma) or iron overload (hemochromatosis) must be evaluated before proceeding to pituitary MRI.

Key Concept

The diagnostic algorithm for male hypogonadism requires sequential confirmation: initial morning screening, followed by confirmatory morning testing (including free testosterone if SHBG is altered), localization with LH/FSH, and specific etiologic laboratory workup (e.g., prolactin, iron) prior to neuroimaging.
Estimated Time:2m 0s
PreviousPage 131 / 237Next